1. Field of the Invention
This invention relates to a sheet conveying apparatus, a sheet feeding apparatus, and a sheet delivering apparatus for feeding or delivering original documents and recording sheets to an image forming apparatus such as a printer, facsimile machine, or photocopier.
2. Description of Prior Art
Image forming apparatuses such as printers, facsimile machines, and photocopiers are recently produced with high performance in accordance with increased processing speed, and have a trend to increase the capacity of the sheet stacking apparatus and the sheet delivering apparatus.
Such an image forming apparatus capable of processing sheets in a large volume can be used in coupling with, in meeting usage of the users, large capacity sheet feeding apparatus or sheet stacking apparatus (sheet processing apparatus) as their optional choices.
A type of the large capacity sheet conveying apparatuses has sheet containing means and feeding means provided on left and right sides. In this sheet feeding apparatus, the conveyance route from one sheet containing means is disposed over the other sheet containing means and the feeding means.
FIG. 8 shows such a conventional apparatus. The conventional image forming apparatus X is constituted of a lower sheet feeding apparatus 300 and an upper laser beam printer 400. In this sheet feeding apparatus 300, a sheet S fed from a left side sheet containing means 303 by a feeding means 305 passes through a conveyance route 306 placed above a right side sheet containing means 304 and is sent to the image forming apparatus after merging with a conveyance route 307 from the right side sheet containing means 304. Position sensor units 301, 302 are formed on the right and left sides slightly before the merging point to detect the sheet position. The sensor unit is constituted of a flag, a rotary shaft of a flag, and a photo sensor. In the laser beam printer 400, a sheet conveyance route 402 extends from a tray stacking sheets S and reaches a delivery tray 405 by way of a process cartridge 407 and a fixing means 404, as the image forming means. An option conveyance route 406 in connection with the conveyance route 310 integrating the two conveyance routes 302, 307 at the sheet feeding apparatus 300 as described above merges to the sheet conveyance route 402.
In the sheet feeding apparatus, however, a merging space is required in a vertical direction because the conveyance route from the left side sheet containing means and the right side sheet containing means are merged in the sheet feeding apparatus, so that the stacking height of the right and left side sheet containing means is limited, and so that the sheet feeding apparatus cannot store many sheets.
The position sensor units 301, 302 for the left side sheet containing means and the right side sheet containing means are placed independently at positions separating from one another, and therefore, wiring for the photo sensor becomes complicated, and the apparatus becomes expensive since a pair of the flag rotary shafts and sensor holders has to be provided.
An invented structure to accomplish the above objects has a sheet conveying apparatus characterized in including a first unit and a second unit formed with a space between the first and second units, the first unit including a first sheet conveyance route, a second sheet conveyance route, a first delivery opening for delivering, from the first unit, a sheet or sheets from the first sheet conveyance route, and a second delivery opening for delivering, from the second unit, a sheet or sheets from the second sheet conveyance route, the second unit having a third sheet conveyance route, and a single introduction opening for introducing, to the third sheet conveyance route, a sheet or sheets delivered from the first delivery opening and the second delivery opening, and a guide member, disposed at a space between the first unit and the second unit, having a first guide surface for guiding the sheet or sheets from the first delivery opening to the introduction opening, and a second guide surface for guiding the sheet or sheets from the second delivery opening to the introduction opening.
According to the invention, because the guide member, at least partly, is disposed between the first unit and the second unit, the merging point of the plural conveyance routes can be placed in the space between the units, and therefore, the first unit can be made compact. Particularly, where the first unit is a sheet feeding apparatus for feeding the sheet to the second unit having the image forming means, the conveyance route can be placed at a further upper position, and the sheet stacking amount can be made relatively larger.
In another aspect, an invented sheet feeding apparatus includes a detecting means for detecting whether any sheet exists in two sheet conveyance routes located adjacently. The detecting means includes in a region between the two conveyance routes two sensors, a rotary shaft, and two sensor flags rotatably with respect to the rotary shaft, placed at a position for shielding each conveyance route. Each of the sensor flags has a region that a contacting portion of the flag in contact with the sheet coincides with each other in a sheet width direction as the perpendicular direction to the sheet conveyance direction. With the guide member having the sensor thus structured, the plural conveyance routes can be detected with such a simple structure.